Field
Embodiments of the invention relate to the field of ambient light sensors; and more specifically, to ambient light sensors with cancellation of internal light sources.
Background
Electronic devices may include devices that emit light and devices that sense light. For example, a device may provide a display screen, such as a light emitting diode (LED) panel, and an ambient light sensor that detects an ambient light level that in turn is used to control the brightness of the display screen. It is necessary to avoid having light from the devices that emit light fall on the devices that sense light to provide accurate sensing. This may be done by physically separating the devices that emit light from the devices that sense light. For example, the devices that emit light may be viewed through apertures in a device housing that are separate from other apertures in the device housing that admit light to the devices that sense light.
Generally it is desirable to minimize the number of apertures in the device housing both to better seal the housing for the protection of the contained components and to improve the aesthetics of the housing. A display screen and other devices that emit light are sometimes mounted below a transparent surface that forms a surface of the device housing. It would be desirable to provide a structure that allows devices that emit light and devices that sense light to be mounted below the same transparent surface of the device housing while minimizing the effect of light from the devices that emit light on the devices that sense light to provide accurate sensing.